Vibration motor controller, and lens apparatus and image pickup apparatus that include the same

Abstract

A vibration motor controller controls driving velocity of a vibration motor relatively moving a vibrator and a contactor contacting the vibrator, the vibrator oscillated by an electromechanical energy transducer to which first and second frequency signals having a phase difference are applied, and includes a phase difference determiner storing a relationship between the frequency and phase difference between the first and second frequency signals, and determines the phase difference with respect to the frequency based on the relationship, and a controller controlling velocity of the vibration motor based on the frequency of the first and second frequency signals and the phase difference determined by the phase difference determiner based on the frequency. The relationship between the frequency and phase difference in the phase difference determiner does not include a relationship between frequency lower than a resonance frequency in frequency-velocity characteristics of the vibration motor, and the phase difference.

What is claimed is: 
     
       1. A vibration motor controller for controlling driving velocity of a vibration motor that relatively moves a vibrator and a contactor in contact with the vibrator, the vibrator oscillated by an electromechanical energy transducer to which a first frequency signal and a second frequency signal having a phase difference are applied,
 the vibration motor controller comprising: 
 a phase difference determiner that stores a relationship between a frequency and the phase difference between the first and second frequency signals, and determines the phase difference with respect to the frequency based on the relationship; and 
 a controller that controls velocity of the vibration motor based on the frequency of the first and second frequency signals and the phase difference determined by the phase difference determiner based on the frequency, wherein 
 the relationship between the frequency and the phase difference stored in the phase difference determiner does not include a relationship between a frequency lower than a resonance frequency in frequency-velocity characteristics of the vibration motor, and the phase difference. 
 
     
     
       2. The vibration motor controller according to  claim 1 , wherein the velocity of the vibration motor based on the relationship between the frequency and the phase difference stored in the phase difference determiner has a range in which the velocity is linear relative to the frequency in a control range. 
     
     
       3. The vibration motor controller according to  claim 2 , wherein the range in which the velocity of the vibration motor based on the relationship between the frequency and the phase difference stored in the phase difference determiner is linear relative to the frequency includes the lowest velocity in the control range. 
     
     
       4. The vibration motor controller according to  claim 2 , wherein the range in which the velocity of the vibration motor based on the relationship between the frequency and the phase difference stored in the phase difference determiner is linear relative to the frequency does not include a range from the highest velocity in the control range to a first velocity lower than the highest velocity. 
     
     
       5. The vibration motor controller according to  claim 4 , wherein the phase difference determiner stores a relationship in which the frequency changes with respect to a constant phase difference, as a relationship between the frequency and the phase difference in the range from the highest velocity in the control range to the first velocity. 
     
     
       6. The vibration motor controller according to  claim 2 , wherein the range in which the velocity of the vibration motor based on the relationship between a frequency and the phase difference stored in the phase difference determiner is linear relative to the frequency includes the highest velocity in the control range. 
     
     
       7. The vibration motor controller according to  claim 2 , wherein the resonance frequency in frequency-velocity characteristics of the vibration motor is a frequency at which the highest velocity is reached under a condition where the phase difference is kept constant. 
     
     
       8. A lens apparatus comprising:
 a movable optical member; 
 a vibration motor that drives the movable optical member; and 
 a vibration motor controller as a controller for the vibration motor, wherein the vibration motor controller controls driving velocity of a vibration motor that relatively moves a vibrator and a contactor in contact with the vibrator which is oscillated by an electromechanical energy transducer to which a first frequency signal and a second frequency signal having a phase difference are applied, 
 the vibration motor controller comprising:
 a phase difference determiner that stores a relationship between a frequency and the phase difference between the first and second frequency signals, and determines the phase difference with respect to the frequency based on the relationship; and 
 a controller that controls velocity of the vibration motor based on the frequency of the first and second frequency signals and the phase difference determined by the phase difference determiner based on the frequency, wherein the relationship between the frequency and the phase difference stored in the phase difference determiner does not include a relationship between a frequency lower than a resonance frequency in frequency-velocity characteristics of the vibration motor, and the phase difference. 
 
 
     
     
       9. An image pickup apparatus comprising:
 a lens apparatus; and 
 an image pickup element that captures an optical image formed by the lens apparatus, 
 the lens apparatus comprising:
 a movable optical member; 
 a vibration motor that drives the movable optical member; and 
 a vibration motor controller as a controller for the vibration motor, wherein the vibration motor controller controls driving velocity of a vibration motor that relatively moves a vibrator and a contactor in contact with the vibrator which is oscillated by an electromechanical energy transducer to which a first frequency signal and a second frequency signal having a phase difference are applied, 
 the vibration motor controller comprising:
 a phase difference determiner that stores a relationship between a frequency and the phase difference between the first and second frequency signals, and determines the phase difference with respect to the frequency based on the relationship; and 
 a controller that controls velocity of the vibration motor based on the frequency of the first and second frequency signals and the phase difference determined by the phase difference determiner based on the frequency, wherein the relationship between the frequency and the phase difference stored in the phase difference determiner does not include a relationship between a frequency lower than a resonance frequency in frequency-velocity characteristics of the vibration motor, and the phase difference. 
 
 
 
     
     
       10. A vibration motor controller for controlling driving velocity of a vibration motor that relatively moves a vibrator and a contactor in contact with the vibrator, the vibrator oscillated by an electromechanical energy transducer to which a first frequency signal and a second frequency signal having a phase difference are applied,
 the vibration motor controller comprising: 
 a phase difference determiner that stores a relationship between a frequency and the phase difference between the first and second frequency signals, and determines the phase difference with respect to the frequency based on the relationship; and 
 a controller that controls velocity of the vibration motor based on the frequency of the first and second frequency signals and the phase difference determined by the phase difference determiner based on the frequency, 
 wherein the velocity of the vibration motor based on the relationship between the frequency and the phase difference stored in the phase difference determiner has a range in which the velocity is linear relative to the frequency in a control range. 
 
     
     
       11. A lens apparatus comprising:
 a movable optical member; 
 a vibration motor that drives the movable optical member; and 
 a vibration motor controller as a controller for the vibration motor, wherein the vibration motor controller controls driving velocity of a vibration motor that relatively moves a vibrator and a contactor in contact with the vibrator which is oscillated by an electromechanical energy transducer to which a first frequency signal and a second frequency signal having a phase difference are applied, 
 the vibration motor controller comprising:
 a phase difference determiner that stores a relationship between a frequency and the phase difference between the first and second frequency signals, and determines the phase difference with respect to the frequency based on the relationship; and 
 a controller that controls velocity of the vibration motor based on the frequency of the first and second frequency signals and the phase difference determined by the phase difference determiner based on the frequency, 
 
 wherein the velocity of the vibration motor based on the relationship between the frequency and the phase difference stored in the phase difference determiner has a range in which the velocity is linear relative to the frequency in a control range. 
 
     
     
       12. An image pickup apparatus comprising:
 a lens apparatus; and 
 an image pickup element that captures an optical image formed by the lens apparatus, 
 the lens apparatus comprising:
 a movable optical member; 
 a vibration motor that drives the movable optical member; and 
 a vibration motor controller as a controller for the vibration motor, wherein the vibration motor controller controls driving velocity of a vibration motor that relatively moves a vibrator and a contactor in contact with the vibrator which is oscillated by an electromechanical energy transducer to which a first frequency signal and a second frequency signal having a phase difference are applied, 
 the vibration motor controller comprising:
 a phase difference determiner that stores a relationship between a frequency and the phase difference between the first and second frequency signals, and determines the phase difference with respect to the frequency based on the relationship; and 
 a controller that controls velocity of the vibration motor based on the frequency of the first and second frequency signals and the phase difference determined by the phase difference determiner based on the frequency, 
 
 
 wherein the velocity of the vibration motor based on the relationship between the frequency and the phase difference stored in the phase difference determiner has a range in which the velocity is linear relative to the frequency in a control range.